Pneumatic hammer



E. CURTI PNEUMATIC HAMMER Filed Aug. 11.

2 Sheets-Sheet 1 MI E/ E. CURTI PNEUMAT I C HAMMER Filed Aug. 11. 1 920. 2 sheets-$11651 2 Patented July 22, 1924.

UNITED STATES ERNESTO CUR-TI, OF MILAN, ITALY.

PNEUMATIC HAlVIlVIER.

Application filed August 11, 1920. Serial No. 402,763.

To all whom/tummy concern.

Be it known that I, ERNESTO CURTI, residing at 20 Via Carlo Farini, Milan, in the Kingdom of Italy, have invented new and useful Improvements in Pneumatic Hammers, of which the following is a specification.

This invention relates to improvements in pneumatic hammers of the type in which the variations of air from an air pulsating compressor or 'pulsator automatically rotates the tool on its own axis. This rotation in many applications is required either because necessary to the drilling operation, or for secur- 'ing greater accuracy during working.

This and other im rovements to be hereinafter described are il ustrated in the annexed drawing inwhich:

Figure 1 is an axial'sectional view of the hammer. g Fig. 2 is a sectional view on the line 2-2 of Figure 1.

Fig. 3 is a sectional view on the line 33 of Figure 1. x

Fig. i is an axial sectional view of a modified form of hammer adapted to function as a drill.

Fig. 5 is a plan view of the same with the cover removed for the purpose of clearness.

In the embodiment of the invention illustrated in Figs. 1 to 3 the hammer includes a cylinder 4 in which is slidably mounted the tappet 3 having a stem which is adapted to strike against the head 7 of the tool 6. The cylinder 4: is provided with a handle 5 adapted to be grasped by the operator for the purpose of manipulating the tool. As shown in Figure 1, the hammer is provided with two air pipes or connections 1 and 2 adapted to be connected to the hose which extends to the pulsator (not shown). The cylinder 4 of the hammer has an extension connected to it by means of a flange and consisting essen tially of a cylindrical part 13 which is in axial alignment: with .the axis of. the cylinder 4:. The extension is also provided with a side member 16 having a cylindrical bore whose axis is-arranged ina plane at. right angles to the axis of the cylinder 4. Arranged in the cylinder 13 is a bushing 8 in which reciprocates the stem of the tappet 3.

The inner surface of the lower dpart of the bushmg is square in shape in or r to grasp the squareend 7 of the tool 6, so that the tool may rotate with said bushing. This rotary motion of the bushing is intermittent and is secured by means of the reciprocating driving piston 15 which is mounted in the bore of the cylinder 16 and actuates a pawl and ratchet mechanism connected to the bushing.

During the operation of the hammer, the i piston 15', which has two disks at its ends, is reciprocated and'the reciprocal movement is limited and counteracted by springs 25 bearing against the disks of the piston. The

movement of the piston 15 is imparted to a V small wheel 1% mounted on an arm 14' extending from a" pivoted collar 10, which is arranged to oscillate about its own axis. This collar cooperates with rollers 11 mount ed in wedge shaped notches provided in a ing 8 in the direction shown by the arrow in Figure 2.

For the purpose of preventing the bush-, ing 8 from rotating in an opposite direction or in the direction of the arrow shown in Figure 3, the cylinder 13 is provided with wedge shaped notches in which. are mounted rollers 12. It will be noted that the narrow ends of the notches for the rollers 11 extend in a direction opposite to that of the narrow ends of the notches in which the rollers 12 are mounted, so that the bushing 8 will be drivenin one direction only.

The bore of the cylinder 16 communicates with an opening in which the valve seat 18 is arranged. This valve seat cooperates with a diaphragm valve 19 which controls the placing, of the bore of the cylinder'16 in communication with a chamber 20 arranged beneath the same. The chamber 20 is provided with a port 21 placing the same in communication with a conduit 22, which communicates with the interior of the bushing 8 by means of apertures 23. The tool 6' is provided with an air passageway 24 which is in constant communication with the air conduit 22. i

The interior of the cylinder 4:- communicateswith the interior of the cylinder 16. by

means .ofail passageways 17 the rollers 11 to drive the flange 9 and bushreciprocating the doublelpiston 15.

In operation, the movement of the tappet 3 is obtained by means of the successive and alternate suctions and compressions of air produced by the pulsator and acting on the hammer through the two pipes (not shown) that are connected to the inlets 1 and 2."

transmitted While 7 the air pulsations through the inlet 1 have no special act-ion except that of raising and lowering thethe pressure of the pulsator acts thereon;

This pressure before distributing itself through the bore of the cylinder 16, acts'on the face of the piston which it first strikes and causes the'piston to move toward the closed end of the cylinder 16. As the piston thus moves, the air entering though inlet 2 distributes itself into the partsin communication with the bore of the cylinder 16.

At this time, suction is exerted through the inlet 2 by the pulsator and this tendsto draw the-piston 15 back to its original vposie tionL The reciprocation of the piston 15, causes the arm 14 to oscillate the collar 10 and consequently to'rotate the bushing 8.. I

The air entering through the inlet 2 in addition to forcing the piston 15 towards,

the closed end of the cylinder 16 tends to force the air through the diaphragm l9 and this permits said air to pass into the chamber 20. When the air in the chamber 20 is of greater pressure than the air in the rear of the cylinder 16,- the valve 19 will be closed. The tappet 3 moves up and down striking against the tool 6 and at the same time the bushing 8 rotates the tool. When the tappet falls on the tool, itsstem compresses air in the inner cavity of the bushing and this pressure through the holes 23 extends to the conduit 22 and then through the opening 21 into the chamber 20. At the time that the air is forced through the opening 21 into the chamber 20 a suction is taking place through the inlet 25. Consequently the valve 19 will be closed while the bore of the cylinder-16 is exhausted. When the air from the bushing 8 has filled the conduit22, the opening 21 and chamber 20, it begins to escape through the duct 24: and consequently a blast of air is delivered to the tool. In the successive phase, the'tappet 3 in rising has a tendency to create a vacuum within the bushing 8 and as the tappet rises pressure air is entering through the inlet 2 and forcing the piston 15. through the closed end of the cylinder 16', so that the suction created by the rising of thetappet' 3 and the pressure exerted by the air entering through inlet 2 have a tendency to fill the chamber 20, the opening 21, the conduit 22 and the interior of the bushing8 withai'r,and a certain'amount of this air escapesthrough the duct 24. Consequently air will be escaping from the duct 24 continuously during the operation of the hammer. It will be understood that these operations may only take place practically when the pulsations are of sufiicient frequency.

In the embodiment of the invention shown in'Figures 4 and 5', the apparatus. is" con structed to function as a drill and inthis instance the tappet 3 and its cooperating parts are eliminated.- In this case the inlet's 1 and 2 convey the air to and from the pulsat'or to and from the" piston 15 which reciprocates within a cylinder 16? pro vided with springs 25Fthat bear against the ends of the piston. In this case theupper end of the bushing 8 is provided with a ratchet wheel 9?, theteeth of which are enigaged by a pawl oarriedby the oscillating collar 10 The oscillatingcollar in this instance has an arm supporting a rollerlflt. that s mounted between two disksfcarried by the piston 15?. The bushing 8 is" We vided with a socket 26 adapted to receive the upper end of the drilling tool andthe bushing 8 is mounted to rotate in a casing A 13 provided with a cover 27 having'azhole 5 to receive a handle (not shown) thatmay be employed in manipulatingthe apparatus; A thrust bearing 28 is mounted within the cover 27 and is adapted to bearagainst the 7,

upper end of th'ebushing 8 It will be noted that the piston 15 is provided with four disks, two of which form the ends of the piston. and the other two 'ofwhich fQIHLZLbUtIHBIltS to actuate the roller 14*. This construction is particularly useful where itis necessary for. thetool to overcome a considerable working resistance.

From the foregoing I believe that the construction, operation and advantages ofthe departing from the spirit of the invention 1 as expressed in the following claims.

"invention will be readily understood, and I am aware that var ous changes maybe 7 l/Vhat I. claim and desire to secure 'b y Letters Patent is In a pneumatic hammer, a cylinder provi'dedat one .end with. an air passageway adapted to be connected with a :pulsator, a hammer. slidably mounted in said cylinder and provided witha stein, a'cylinder extension connected to one: end of the cylinder and provided with a rotatable j bushing i'n whichlsai'dstern is" slidably mounted, a't'o ol r tedbyv f ei bush ng, a S n cy i der a ry ei r ei'nreset ne risen an i pr d w th mp e w y a ap e amm nieatewiui pulsator, and a ratchet and pawl mechanism adapted to rotate said bushing duct and With the interior of said bushing, and actuated by said piston, a chamber, a and ports placing the interior of the first pressure actuated Valve controlling the pasmentioned cylinder in communication with 10 sage of air from the interior of the second the interior of the second cylinder.

cylinder to the chamber, a duct arranged In testimony whereof I aflix my signain said tool, air conduits placing the interior ture.

of said chamber in communication with said ERNESTO GURTI. 

